The invention relates to metal base terminals for electric lamps and devices having sealed envelopes of vitreous material provided with an externally extending flat pinch seal at an end. It is particularly useful with tubular double-ended incandescent lamps and heat lamps of the tungsten halogen cycle kind utilizing fused silica envelopes. In such lamps the inleads generally include extremely thin flattened ribbon or foil portions which are embedded in and sealed through the wall of the fused silica envelope by collapsing and fusing the silica firmly around the foil in a so-called flat pinch seal. In use, the lamp is generally supported by accommodating the pinch seals at each end in spring metal support clips which may also serve as current connectors to the inleads.
It has been the general practice up to now to provide a base terminal comprising a thin-walled metal sleeve wrapped and clamped around the pinch seal to facilitate accommodating the pinch seal in the spring support clip. In one construction the base is connected to the externally projecting portion of the inlead which then serves as a terminal. In another construction a flexible pigtail is connected to the inlead and the function of the base then is primarily mechanical and decorative. Such base terminals are described in U.S. Pat. No. 2,705,310 -- Hodge, and comprise a flattened metal sleeve which is stretched tightly around the pinch seal by folding or welding together a seam along one side.
The mounting of bases of the foregoing kind on the lamp ends is rather laborious and there is inevitably some shrinkage by cracking of seals during assembly. The object of the invention is to provide an improved base structure serviceable also as a terminal, which is low in cost, easily assembled, and reliable in service.